A Mexican-roadblock occurs on a two or more lane road where 2 (or more) cars are traveling next to eachother at the same speed (usually under the speed limit), not allowing the following traffic to pass. Most noticeable on the highway in a light traffic situation, where two cars stop the flow of traffic wishing to pass.

i was late to work because i got stuck behind stuck behind a mexican-roadblock

When driving on a road with two or more lanes going in one direction, and vehicles occupy all lanes. Said vehicles drive at the same speed and evenly, barring other vehicles from passing. This event native to Denver, where many "undocumented workers" usually from Mexico attempt to drive without a valid driver's license or automotive insurance. These illegal immigrants therefore drive significantly under the speed limit, effectively infuriating all other drivers on the road.

Sorry I'm late for work today Mr. Jenkins. There was a Mexican road block on Interstate 25.

(n) May be created intentionally or unintentionally- two cars driving next to each other at the exact same speed, thus preventing you and other cars behind from passing. Unbelievably frustrating, especially when you have somewhere to be.

Always happens when I'm late to work.

I try to move to the right lane to prevent creating a Mexican roadblock.